Circular sleeve coupling



FIG. 1 is a perspective view of a circular sleeve coupling, showing our new design, as seen obliquely from the front;

FIG. 2 is a perspective view of the sleeve coupling, as seen obliquely from the back;

FIG. 3 is a side elevation of the sleeve coupling, the opposite side being a mirror image thereto; and,

FIG. 4 is a front view of the sleeve coupling. 

The ornamental design for a circular sleeve coupling, as shown and described. 